Fans cheer Golden State Warriors guard Stephen Curry (30) during the second half of Game 2 of the NBA basketball Western Conference finals against the Houston Rockets in Oakland, Calif., Thursday, May 21, 2015. (AP Photo/Rick Bowmer)

With the Golden State Warriors on the brink of their first NBA title in 40 years, Bay Area cities are preparing for celebrations potentially turning into riots.

The Warriors, with a 3-2 series lead over the Cleveland Cavaliers, could clinch the series with a victory this evening in Cleveland. A Cleveland victory tonight would push the series to a seventh game, scheduled for Friday in Oakland.

While the Warriors’ current home is in Oakland, their fan base reaches across the Bay and the team is slated to move to San Francisco in a few years.

An Oakland sports team last brought home a championship in 1989, but the San Francisco Giants have experience with three recent World Series victories, including the sometimes destructive celebrations that follow.

Giants fans have smashed buses, lit fires, and pelted police with bottles as they streamed into city streets following the World Series victories in 2010, 2012 and 2014.

San Francisco police spokeswoman Officer Grace Gatpandan said that means that officers are experienced and ready for what may follow a Warriors victory.

The department has canceled some officers’ days off in preparation, and will be providing extra staff in “celebratory locations,” including in the South of Market and Marina neighborhoods, along Polk Street and in the Mission District.

“We’re prepared to act, we want to facilitate people and make sure they have fun,” Gatpandan said, but officers will move in quickly if they see anyone trying to loot, start fires or start a riot.

“We are prepared for the Warriors to win and hopefully they do so,” she said.

Such situations can escalate quickly, as celebrations in the Mission District took a sudden turn last year with crowds of revelers suddenly turning on police there and throwing bottles at them.

Officers will not be wearing riot gear as they patrol city streets, but will have it readily available in case the crowd turns ugly, Gatpandan said.

While there have been no similar celebrations in Oakland recently, there were riots following the Oakland Raiders’ loss in the 2003 Super Bowl and there has often been vandalism during the city’s frequent protests.

An open letter from interim City Administrator John Flores said the city is prepared for “exuberant” celebrations and large crowds taking over city streets.

“The city of Oakland will be prepared to maintain a safe environment for all to enjoy the pre- and post-game celebrations,” Flores said. “Our entire city family will be working hard to put Oakland’s best foot forward, keeping the city clean and making sure that the world knows what a great host Oakland has been for the Finals.”

Oakland police did not provide comment on the department’s specific plans or preparations this morning.